A popular form of jewelry is the heishi necklace made of tubular beads cut from turquoise, shell, coral, as well as other hard materials and strung in a desired pattern on a stringing cord. To cut these beads from hard materials it is necessary to drill the center hole and to shape the beads individually to the desired circular shape in separate steps.
A primary object of this invention is to provide an adjustable core drill and hole drill which can simultaneously cut both a cylindrically shaped bead and drill a hole in the center thereof.